Yes, you can do that.
jd'info ref' NB. list ref cols
jd'dropcol colnam'
https://code.jsoftware.com/wiki/Jd/Ops_info#info
https://code.jsoftware.com/wiki/Jd/Ops_drop#dropcol
On Thu, Feb 10, 2022 at 5:44 PM Raul Miller <rauldmil...@gmail.com> wrote:
> Excellent, thanks. Adding 'first' to the other column labels is easy
> and makes sense to me.
>
> One other question: currently to test the script I am writing, I am
> having to delete the jd files from outside of J. If I fail to do that,
> I get the error "|Jd error: table has ref: op:droptable db:csvload"
> when I re-run my script.
>
> In this context, I do not want to protect the data -- in this context,
> testing my script for unexpected dependencies is key. Is there some
> way of dropping that ref?
>
> Thanks,
>
> --
> Raul
>
> On Thu, Feb 10, 2022 at 2:42 PM Eric Iverson <eric.b.iver...@gmail.com>
> wrote:
> >
> > Take a look at https://code.jsoftware.com/wiki/Jd if you have not
> already
> > done so.
> >
> > The docs are weak and we depend more on the tutorials. There are
> tutorials
> > that cover the area you are interested in.
> >
> > I loaded your files and have taken a quick look.
> >
> > First, I removed all the col relabel stuff as it is noise (and at times
> in
> > the past has triggered bugs). That is, remove all the txt: and other
> stuff
> > to make the statement as simple as possible.
> >
> > The by clause requires that there be an aggregation function for each col
> > in the select clause. That is the important part you were missing,
> although
> > the error was quite misleading.
> >
> > The following is a simple statement that works and has all the important
> > elements from your example.
> >
> >
> > jd'reads count patients.LASTNAME , count visits.VISIT_DATE by
> > patients.PATIENTID from patients, patients.visits'
> >
> > Perhaps it will help you get further along.
> >
> > If you get stuck again or are still stuck, please ask again.
> >
> > On Thu, Feb 10, 2022 at 2:12 PM Raul Miller <rauldmil...@gmail.com>
> wrote:
> >
> > > Embarrassing mis-statement:
> > >
> > > I wrote: "I am not trying to learn Jd"
> > >
> > > I meant: I am *now* trying to learn Jd
> > >
> > > --
> > > Raul
> > >
> > > On Thu, Feb 10, 2022 at 1:58 PM Raul Miller <rauldmil...@gmail.com>
> wrote:
> > > >
> > > > http://rosettacode.org/wiki/Merge_and_aggregate_datasets
> > > >
> > > > After looking at this rosettacode task, I decided that Jd is probably
> > > > best suited for the J task implementation. So, I am not trying to
> > > > learn Jd (I had not had occasion to use it, previously).
> > > >
> > > > After a few minor mishaps, I've stumbled on an issue which I do not
> > > > know how to resolve.
> > > >
> > > > (Previous mishaps: csvload fails with an error suggesting that the
> > > > file does not exist if csvprepare has not been previously run. This
> > > > behavior is undocumented, except by example in the tutorials. Also, I
> > > > need to run the tutorial in a different J session from my testing
> work
> > > > to prevent the tutorials from breaking my tests.)
> > > >
> > > > Anyways, I'm currently getting an Unrecognized aggregate function
> > > > error, when trying to use the 'max' aggregate function. This should
> > > > demonstrate where I'm at:
> > > >
> > > > require'jd pacman'
> > > > load JDP,'tools/csv_load.ijs'
> > > > F=: jpath '~temp/rosettacode/example/CSV'
> > > > jdcreatefolder_jd_ CSVFOLDER=: F
> > > >
> > > > assert 0<{{)n
> > > > PATIENTID,LASTNAME
> > > > 1001,Hopper
> > > > 4004,Wirth
> > > > 3003,Kemeny
> > > > 2002,Gosling
> > > > 5005,Kurtz
> > > > }} fwrite F,'patients.csv'
> > > >
> > > > assert 0<{{)n
> > > > PATIENTID,VISIT_DATE,SCORE
> > > > 2002,2020-09-10,6.8
> > > > 1001,2020-09-17,5.5
> > > > 4004,2020-09-24,8.4
> > > > 2002,2020-10-08,
> > > > 1001,,6.6
> > > > 3003,2020-11-12,
> > > > 4004,2020-11-05,7.0
> > > > 1001,2020-11-19,5.3
> > > > }} fwrite F,'visits.csv'
> > > >
> > > > csvprepare 'patients';F,'patients.csv'
> > > > csvprepare 'visits';F,'visits.csv'
> > > >
> > > > csvload 'patients';1
> > > > csvload 'visits';1
> > > >
> > > > jd'ref patients PATIENTID visits PATIENTID'
> > > >
> > > > echo jd ([echo) deb {{)n
> > > > reads
> > > > p.PATIENTID,
> > > > LASTNAME:p.LASTNAME,
> > > > first v.VISIT_DATE
> > > > by
> > > > p.PATIENTID
> > > > from
> > > > p:patients,
> > > > v:p.visits
> > > > }} -.LF
> > > >
> > > > Now, ... one of my thoughts was that maybe this is a type error,
> > > > indicating that 'max' does not have a definition for the type of data
> > > > in this column. However, replacing 'max' with 'first' (which should
> be
> > > > defined for any type of column) also gives an "Unrecognized aggregate
> > > > function' error.
> > > >
> > > > So...
> > > >
> > > > (1) What am I doing wrong here, and
> > > >
> > > > (2) What should I have looked at to discover this information?
> > > >
> > > > Thanks,
> > > >
> > > > --
> > > > Raul
> > > ----------------------------------------------------------------------
> > > For information about J forums see http://www.jsoftware.com/forums.htm
> > >
> > ----------------------------------------------------------------------
> > For information about J forums see http://www.jsoftware.com/forums.htm
> ----------------------------------------------------------------------
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